R. Short, F. Clara
In the ongoing effort to mitigate the 9.5Hz comb recently found to be coming from the PSL flow meters (alog79533), this afternoon Fil put the PSL control box in the LVEA PSL racks on its own, separate 24V bench-top power supply. Once I shut down the PSL in a controlled manner (in order of ISS, FSS, PMC, AMP2, AMP1, NPRO, chiller), Fil switched CB1 to the separate power supply, then I brought the system back up without any issues. I'm leaving the ISS off for now while the system warms back up. I'm leaving WP12051 open for now until enough data can be collected to say whether this separate supply helps the 9.5Hz comb or not.
Please be aware of the new power supply cable running from under the table outside the PSL enclosure to behind the racks; Fil placed a cone here to warn of the potential trip hazard.
This looks promising! I have attached a comparison with a high-resolution daily spectrum from July (orange) vs yesterday (black), zoomed in on a strong peak of the 9.5 Hz comb triplet. Note that the markers tag the approximate average peak position of the combs from O4a, so they are a couple of bins off from the actual positions of the July peaks.